776 VII. LIPID DISTRIBUTION IN SPECIFIC TISSUES 



9. Lipids Present in the Skin and Its Appendages 



(1) General Distribution of the Lipids 



The skin not only represents one of the most extensive organs of the body, 

 but it also possesses varied physiologic functions and specialized meta- 

 bolic patterns which contribute to its importance. Lipids play an impor- 

 tant role in these several functions of the skin. The metabolism and per- 

 meability of normal skin was reviewed in 1946 by Calvery et al. S97 



The first comprehensive study of the composition of skin lipids was that 

 of Unna and Golodetz, 398 who reported chiefly on the cholesterol distribu- 

 tion in human skin, as affected by various metabolic processes. Ac- 

 cording to Jono, 399 human skin contains 2% of lipids. Eckstein and Wile 400 

 found that cholesterol occurred in exfoliated human skin to the extent of 13 

 to 24% of the total lipids; approximately 90% of the cholesterol was 

 present in free form. Phospholipid was found to constitute only about 

 3% of the total skin lipids. Pachur 401 reported similar analyses of the 

 human skin surface. He found 88.26% neutral fat, 4.2% cholesterol esters, 

 phosphatides and soaps, and 7.54% cholesterol. 



However, differences in the results of several investigators have been 

 difficult to evaluate because of the variations in the source of the samples. 

 Differences exist in the lipid nature of the various strata of the skin. 

 In order to obtain a serial picture of the composition of skin lipids as re- 

 lated to the portion of the skin from which they were obtained, Koppen- 

 hoefer 402 - 403 compared the lipid composition in six histologically distinct 

 horizontal layers. These included the epidermal region consisting of hair 

 (1), horny {2) and basal area (3), the transition region (4), and the corium 

 region, which is made up of the corium major (5) and of the corium base (6). 

 In these studies, the skin of steer was employed, since this offered the ad- 

 vantage of being available in large amounts and of being readily separable 

 mechanically into the several different layers. A striking similarity exists 

 between the lipids of human skin and those of steer skin, particularly in 

 regard to their nature and to the pattern of their distribution. Table 20 

 summarizes the data on the composition of lipids in the several layers of 

 steer skin. 



397 H. O. Calvery, J. H. Draize, and E. P. Laug, Physiol. Revs., 26, 495-540 (1946). 



398 P. G. Unna and L. Golodetz, Biochem. Z., 20, 469-502 (1909). 



399 Y. Jono, J. Biochem. {Japan), 10, 311-323 (1928-1929). 



400 H. C. Eckstein and U. J. Wile, J. Biol. Chem., 69, 181-186 (1926). 



401 R. Pachur, Dermatol. Z., 60, 486-490 (1931). 



402 R. M. Koppenhoefer and J. H. Highberger, /. Am. Leather Chem. Assoc., 29, 598- 

 623 (1934). 



« 3 R. M. Koppenhoefer, /. Biol. Chem., 116, 321-341 (1936). 



